Coke oven structure



Jan. 9, 1940.

F. DENIC;4

COKE OVEN STRUCTURE Filed Auga 5, 1957 5 SheetS-Sheet l INVENTOR. Fee@ DEN/G.

Kfm/7;(

Iw ATTORNEY.

Jan. 9, l1940.

F. DENIG COKE OVEN STRUCTURE Filed Aug. 5. 1937 '5 Sheecs-Srheel 4 INVENTOR. F250 DEN/G.

M )(Aa. ATTORNEY.

Jan. 9, 1940. F. DENIG com: ovEN STRUCTURE Filed Aug. 5, 1937 5 Sheets-Sheet 5 INVENTOR. FRED DEN/G. .v/0,7%

Patented Jan. 9, 1940 PATENT OFFICE f y 2,186,237 COKE OVEN STRUCTURE Fred Denig, Pittsburgh, Pa.,` assignor to Koppers Company, a corporation of Delaware Application August 5,

s claims.

The present invention relates to horizontal coking retort ovens of the regenerative type and more especially to those that are provided with accessible passageways beneath the oven-supporting mat, Such, for example, as those passageways wherein are found the distribution systems for the unpreheated underring gas that is supplied to the flame iiues of the so-called underjet coking ovens. y

In a battery of regenerative coking retort ovens the coking chambers are generally disposed in alternation with flued heating walls along its lengthwise dimension. Beneath the coking chambers and the heating walls are checkerbrickfilled regenerative spaces wherein underring gases may be preheated before they are introduced into the flame flues, the heat for such purpose being recovered from the combustion-products subsequent: their leaving the heating flue system and within the regenerative spaces, v Periodically the direction of gaseous flow in the fregenerators and in the flued heating wallsfis reversed so that that heat recovered from the outflowing combustion-products-and stored in the checkerbrick during one interval of the reversal period, is released to the iniiowing fuel gases during the .subsequent interval.` Beneath the bottom of the regenerators is a structural mat that extends beneath the whole battery structure for which it Servesas a support. `This supporting-mat for the battery may rest either directly on the ground Surface orbe elevated therefrom on piers in such manner as to provide accessible passageways therebeneath wherein supply `and 'control devices for supervising the operation of the vovens may be positioned.`

v An 'object of the present invention is the provision of means whereby gases may be flowed between the heating flues of the heating walls andthe regenerative spaces in accurately and facilelyv controlled amounts that are conveniently regulable from the afore-mentioned accessible passageways beneath the battery-supporting mat.

A 'further object of invention is to furnish means that will enable coke oven operators to regulate and control from the relatively cool region beneath the Vbattery-Supporting mat the quantities of gases that are flowed between the regenerators and each of thev heating ilues'with which they communicate so that during operation the iiues will be each assured of having those quantities of gases flowed therethrough as are preferred in consideration of their relative positions inthe heating wall and without subjecting the operators to the laboriousztask of making 1937, Serial No. 157,461 (cl. 2oz- 151) adjustments from the tops of highly incandescent flues.

A further object of invention is the provision of an easily operable means for the foregiven objectives and purposes that will neither operate as an impediment to the flo-W of the gases after they have entered the heating flues nor create undesirable back pressures therein.

The invention has for further objects such other improvements and such other operative advantages or results as may be found to obtain in'they processes or apparatus hereinafter described or claimed. 1

In horizontal coking retort ovens of the regenerative type, each heating ue of a heating wall is communicably connected with at least one therebeneath positioned regenerative space, and in those instances'where the oven structure` is adaptd for operation as a gas oven with extraneously produced underiiring gas of lower thermal content,'which requires preheating for its effective combustion, each flue communicates with at least two separate regenerative spaces the one of which is utilized to preheat underring gas while the other iS used to preheat the air for its combustion. In general, communication between the heating flues and the regenerators is provided by canals orducts that connect at their lower parts with theupper parts of the regenerators and at their upper ends port into the lower parts of the heating` flues. These passageways between the ues andthe 'regenerators commonly pass through theA tops .or capitals 'of those vertical pillar walls that separate the entire regenerative space beneath the oven oors into individual regenerators extending'lengthwise of the coking chambers, and that also support the upper part of the battery structure. The pillar walls each at their lower parts rest on the battery-supporting mat and at their tops support the masonry 'of the flued heating wall and the oven sole immediately above. They are formed from'courses of bricks, and rthose bricks at the upper part of said pillar Walls are appropriately shaped to provide the above-mentioned passageways between the regenerators and the nues.

According to thepresent invention there is supplied'for each ofthe heating flues of a coking oven heating wall and at apoint adjacent the top of its associated pillar wall, a movable refractory brick that is vadapted fory actuation from beneath the battery-supporting mat and in such manner that said brick may be employed to modify as` preferred theeffective cross-section of the passageways that interconnect the heating flues with the regenerative spaces therebeneath thereby making it possible to vary optionally the rate at which gases may flow from the regenerators into the heating flues individually, under the influence of the stack-draft, without that awkwardness and tedium attending the adjusting of sliding bricks or the angling for port regulating media positioned at the bottom of ilues that are highly incandescent. In its preferred form the adjustable gas-flow regulating brick of the invention is positioned in the brickwork adjacent the top of the oven pillar wall and forms a section of the side-walls of the passageways or ducts that communicably connect the regenerators and heating fiues where it is held in position by a stem-like section that is disposed vto rest slideably in a vertically extending shaft that reaches from the top of the pillar wall downwardly therethrough and through the battery-supporting mat and into the accessible passageways beneath said mat. Within each such shaft is slideably disposed a refractory rod or tube which is supported therein by means of a threaded bolt, or the like, that is in turn supported by and adapted to travel through a securing member also located in the battery basement. rI'he refraotory rod may be formed in sections, if preferred, thereby facilitating its installation in the vertical shaft, and it should be of adequate total length to transmit movement of said screw-bolt to that stem-like section of the moveable brick which retains the latter in its designed position. By means of this improvement the coke ovenoperator is provided an implement whereby the eifective cross-sections of those ducts that interconnect regenerators and heating nues, can be optionally varied by appropriate adjustments on regulatory screw-bolts conveniently accessible in the battery basement, thus providing means that are adapted to permit expeditious regulation from that station of preheated air and preheated underring gas that enter the flame ues and without encountering the inconveniences of high temperatures at which metal adjusting implements lose their rigidity, as is the case where control measures must yproceed from the tops of the heating ilues. Additional advantages of the instant improvement reside-in the facts that it is possible to eiect the preferred adjustments with dispatch and that it offers a means of obtaining an improved refinement in the regulation of a batterys underi'lring.

In the accompanying drawings forming a part of this specication and showing for vpurposes of exempliiication a preferred apparatus and method in which the invention may be embodied and practised but without limiting the claimed invention .specically to such illustrative instance or instances:

Figure 1 is a crosswise vertical section through a coke oven battery embodying features of the present improvement, said battery comprisingv coking ovens of the so-called underjet type in which unpreheated underring gases are distributed to the heating iiues from a distribution system therefor positioned in a basement located beneath the battery-supporting mat, the section A-A of the view being taken longitudinally through a coking chamber and along the `line A--A of Figure 2, whereas the section B--B is taken through a heating wall and a pillar wall andalon'g the line B-Bof Figure 2;

Figure 2 is a vertical sectional elevation taken longitudinally of a coke oven battery, portions being shown broken away for clearness yof illustration, and a part of the section being taken in a portion of the battery in the plane indicated .by the lines II-II and the other part of the section being taken through another portion of the battery in the plane IIa-IIa of Figure l;

Figure 3 is an enlarged view of a fragment of the section taken on the line II-II of Figure l and illustrated in Figure 2 and showing certain details of the `present invention and their arrangement with respect to the regenerator ports at the bottom of the heating flues and to the pillar walls of the battery;

Figure 4 is fragmentary vertical sectional View taken ,crosswise of the battery along the line B-B of Figure 2, showing an enlarged fragment of that part of the section B-B of Figure l which involves the pillar wall, rich underfringgas conduits and the improvement offered by the present invention;

Figure 5 is a horizontal section taken along the line V--V of Figure 4;

Figure 6 is an enlarged View of the means provided by the invention and employed to .adjust that amount of the total cross-sectional area of the ducts connecting the regenerators `and the heating ilues, which vis made available for the flow of gases therebetween; and

Figure 7 is a perspective View of the structure shown in enlarged section in Figure .3 but on smaller scale.

v The same characters of reference designate the same partsthroughout the several views `of the drawings. 'Y l Referring now to `the drawings: .the invention as shown in the several views of the drawings is embodied for purposes of exposition in a coke oven battery of the underjet type which is also susceptible of being operated as a gas oven at which times heating of. the coking-chamber walls is-effected by means of la gas of lower caloric value that requires a preheating step before .be-

ing introduced into the iiamerues; .certain of the y regenerators being utilized for that purpose. The flues of any heating wall at oneside vof a coking chamber are communicably connected `at their upper ends with similarly disposed'and grouped ilues of the heating wall at :the opposite side -of said ccking chamber by means of duct means that cross` over the top of said chamber in the well-known manner of the Becker ovens of for instance, his Patent 2,100,762, wherein the combustion-products or waste .gases from any one heating wall are led into the upper ends of the heating iiues at the opposite side' of the intermediate coking chamber. The `benets .provided by the present improvement are not necessarily restricted to coke ovens of the design `illustrated in the drawings but they can be realized in vany regenerative coke oven battery that is supported on piers in such' manner as to provide accessible passageways therebeneath.

The coking retort oven battery shown in `the drawings embodies in its construction a plurality of crosswise elongated heating walls I I, I I and a plurality of intermediate elongated verticalfcoking chambers I2, I2. The heating walls `II form the side walls of the respective `coking chambers I2 as shown particularly in Figures 1 and 2 and are supported in the present instance by heavy supporting pillar walls I3, `I3 that extend cross- `wise of the battery .and are located Yas shown in Figure 2, beneath their respective heating walls.. Thepillar walls I3serve both to support the heating walls and to divide the regenerative space beneath the Aheating walls and the coking chambers into a plurality of gas-tight individual regenerators that extend crosswise of the .battery and in substantial parallelism with the heating walls. Each of the regenerators positioned. between .the pillar walis rI3 is further sub-divided into a regenerator pair by the regenerator division wall I4 which serves to support the coal charge in the coking chamber I2 directly above it and is in addition of such substantial and gas-tight construction that gases may *bey maintained under relatively diierent pressures on the i opposite sides of said division walls I4 so that the flow of diiferent underring media through the checkerbrick containedl in these different regenerator chambers I5 may be maintained without leakages from one chamber to the other taking place.l Each regenerator of a regenerator pair is furnished with an individual sole flue I6 that communicates by means of a plurality of ducts I 1. with the checkerwork above, said ducts operatf ing to promote a uniform distribution throughoutl theregenerator chamber of the gases introduced into theends of sole lues. .The vertical heating fiues I8.of the heating walls each communicatel with two regenerators I5, that are located on opposite sides of the pillar kwalls I3, by. means' of ducts I9 through which the gases, flowed over theregenerator checkerbrick from the sole nues,

pass into the lower part of said heating flues.

Beneath the regenerators is the battery-sup- U porting mat 2l) that is itself supported by piers 2I above the ground, level thereby providing.

passageways 22 inwhich access can be had to the mat from beneath as well as such of the `op erating accessories as may be positioned there;

For the introduction into the heatingflues of unpreheated underiiring gases a` distribution system in the battery basement is. provided. .'The arterial rich gas supplying-main 23 communicates with a reservoir of rich gas outside the bat-F terystructure. Rich gas is flowed therefrom in y quantities regulated by gas-cock 24 intoy distributor header 25, whence said gas ypasses vinto v ducts 26 that rise vertically through the batterysupporting mat and the pillar walls I3 to terminate at the lower part ofthe heating flues at gas-ports 2. A distributor header 25 is provided for each heating wall and a duct 26 rises. thererfromto each iiue therealong. vThe-air destined forv admixture and combustion with unpreheatedy underring gas that is introduced into the heating flues through said ducts 2B, is flowed into all the sole channels I6 from regulable flow-boxes positioned at the outer ends thereof (but .not shown) and subsequent its distribution Iby ducts I'I over the checkerbricks, contained in regenerators I5 for preheating purposes, said air enters y the burning flues at their 'lower' ends through ducts I9; that air which is preheated in those adjacent to and on opposite sides regenerators of the same pillar walls I3 introduced into the heating flues of any one wall through ports 28 that are common to both regenerators vand their ducts I9, as is clearly shown in Figures 3 andy 7. The combustion-products produced by the burning of the rich gas and preheated air rise through iiues IB and pass into short `horizontal ducts 2 9 whence they enter similar heating uesin the wall on the opposite side of a. coking. chamber by way of cross-over ducts 3l? to flow downwardly y,

into other communicating regeneratorsin which waste-heat is accumulated from the combustionproducts as they flow downward and outward therethrough to stack means. y f y Heatliberated by the'reactio'ns of combustion is transferred through the heating walls to the coal charge that has been previously introduced through vcharging holes 3l into the coking chambers I2 that are closed at each end by refractoryklined doors y32. The gases and vapors of distillation are carried away through ascension pipes 33. Periodically the direction of gaseous flow through the regenerator and heating flue systemsy is reversed and the burning flues become the non- .burning ones and the inflowing become the outowing regeneratorsl and vice versa.

At such times as the battery in which the in.-

'vention vis embodied is being' operated for the production of gas of relatively high thermal content, the battery may beunderred with gas of lower heating value' than that resulting from the carboriifzation, and the rich gas supply to the heating flues is cut off byclosing valves 24 that deliver gasto the distributor-headers 25, and the underfiringI gas of `low heating value, ducer or blast furnacegas, is introduced into regenerators for av preheating step, prior to its entering thelheating flues. This method of op- .eratio'nis too welll known in the prior art to need further'co-mment here, but duringsuch periods of operation, in the battery shown in the drawings, it `is `the preferred procedure that during a .re'generativeheating cycle those regenerators i whoseltops are communicably connected b-y heating ilue's that are interconnected, for gasflow purposes, by cross-over ducts that extend upward and over the top of" an oven. adjacent said flues,

' lshall have' said regenerators so arranged in re; v spe'ct' Aof the-regulationand ycontro-l devices for the waste-heat, theair andthe fuel gas that an air regenerator yis always interposed between the combustion-products regenerators `and the regeneratory for preheating fuel gas, and that the regeneratorssfor carrying inflowing fuel gas and combustion air, are adjacent to and on opposite sidesvof thesarne pillar wall I3, (a circumstance which will be considered hereinafter in respect of the present improvement) .j l Under certain operating conditions it is for several reasons highly desirable to regulate: the quantities of air and'underring gases that are introduced into the individual heating flues because,

`asis appreciated by those experienced in the art, -the heat'requirements of each of the plurality of 'heatingflues along an oven wall varies somel of underring gasesflowed intothe separate ues, so that the provision of means whereby the effective cross-sectionl of the ducts that lead from. the regenerators to theheatihg yilues can be altered with great convenience and facility, will be an advantageous contributionto the art.

In the coking retort battery illustrated inthe drawings, two v'regenerators ladjacent opposite sides of the samepillar wall I3 are each connected with a. heating flue I8 by means of ducts I9,` I9. A short distance below the bottom of the heating flue, tlie twoy said ducts gradually converge into a common short duct through which gases from each of the pair of regenerators enter the heating i flue. The cross-sectional area of ducts I9 gradually diminishes asjthey approach their point of convergence where the masonry of the division wall which separates them terminates in a fiat surface 35. Shaft 34 extends from surface 35 downward the entire height of the pillar wall andv through the battery mat to open in the passageways therebeneath. Shiftable brick 35 .which isv formed with inclined sides where it forms a` part.

of the walls of ducts i9 and also has astem-like part 3i attached to its underside, rests loosely on the surface 35 of pillar wall I3 as a sort of nial thereto; the part 3'! being of such size to be easily moveable in the duct 31% at all temperatures of. operation. Accordingtc theinvention said shaft 3i contains a plurality of refractory rods S8, or if preferred pipe-like shapes, that are tted for up and down movement therein by means of the supporting screw-bolt '39" that has a threaded section whereby it is securedin a correspondingly threaded hole of the battery-supporting structural beam 43. Withappropriate turning of the head of screw-boltiby'any suit-' able means, said screw-bolt can be cruised to travel upwards or downwards in beam. Mend to respectively raise or lower the train of refractoryV rods 3S which in turn operates to move brickshape 36 in a corresponding direction by its pressure against the lower part of section 351;' As. is clearly shown in Figure 3, the raising oi brick 36 upward to some such position as is shown by the dotted lines, will'graduallydecrease the distance between the surface of said-briclrand the masonry forming the upper-walls throat 4| of conduits i9, thereby reducing the free-way that is aVailablefOr gas-flow therebetween simultaneously decreasing the volume orgaseons media that is permitted to enter the heating flue from the regenerators during a giveninterval.v I'he member 39 can be turned through a large arc and yet cause the shiftable brick 3e to travel only a relatively short distance, thus the improvement offered by the invention provides easily operable means'for establishing accurate adjustments ofthe effective cross-section of ducts i!! and as a result effects an improved renement in control of the rate at which gases are delivered to the, heating iues.

As hereinabove mentioned, at such times as it is desired to operate as gas ovens the ovens of the battery in which` the invention is embodied,

, one of the two regenerators ladjacent opposite sides of the pillar wall I3 will be periodically operating to preheat `a gas of lowT caloriflc value with the result that during such intervals one duct of an adjacent pair of ducts I9 will be carfrying preheated underring gas to the associatedy heating fluewhile preheated air is flowing upwards through the'other. If then, under suc-h circumstances of operation, shiftable brick :it were elevated above division-wall surface 35-for .l purposes of reducing the gas rate, a pre-mixing and combustion of preheated air and imderfiring gases might take place in the interspace between and thus cause over-heating off the' masonry there-adjacent, if provision were not made to circumvent it. This eventuality is overcome ac- That common section of, a pair of conduits IS, I9',- between their convergence and port 28 is formed. with substantially vertical side Walls and the maximum volume of gases permitted to flow therethrough from the regenerators'into the heating flues ata given pressure differential is determined kby aremovable. port-plug i4 having walls substantially parallel with the` side-walls of said conduit section, so that the preheated gases enter theheating'flues in the form of an annular` ring and. with no tendency to be diverted from a stream-like flow-path by this port. regulating means, which has been disclosed and described in an application for Letters Patent by Joseph van Ackeren applied for on May le, 1936, and assigned Serial Number 79,669. Plug it .is removably supported on'brick-shape 35 by means of a lug i5 that'is formed atone end thereof, said lug being also adapted to be received by socket in the upper surface of the brick-shape 35. The

plug may bev removed or replaced through aflueinspection hole by meansoi' a rod adapted. to engage said plug after, it hasl entered slot si. Itis of course obvious that the areaof porti@ made available'for the flowing oi'gases between the v heating fines` and the regenerators may be varied by using port-plugs having cross-sections-that bear variousrelationships to the total cross-'section ofthe port opening.

An advantage resulting fromv the combination of, a. port-plug of this type and of an adjustable refractory element in the masonry of a regenerator pillar wall by means of which the effective cross-section of conduits connecting heating fries and regenerators may be altered as preferred, resides in the fact that such turbulence or eddying in the stream of issuing gas-es as may be promoted by the presence therein of said refractory element, will tend to be corrected by a concentrically positioned port-plug having side-walls substantially parallel with those of the port-duct, so that gases entering the heating flue will be directed upwards in a substantially vertical flowadvantageously tends to delay combustion somewhat and thus lengthen the flame, It also does not prevent some intermingling of preheated air and preheated underfiring gas before` they enter the heating fiues, thereby promoting more favorable heating conditions at the bottom of the ovens than would otherwise obtain with gases of lower caloric values.

By reason of the present inventiomthe occasion for altering the effective cross-section ofportsi 2B after a battery embodying the improvef ple turning cfa threaded member that is conveniently accessible in the battery basement,

The invention as hereinabove set forth'is embodiedin particular form and manner but may be variously embodied within the scope of the claims hereinafter made.

I claim:

l. In a coking retort oven having accessible passageways beneath a supporting-mat therefor,

path which. in the case of rich gas underiiring- 'aise-,123?

means,andfbeneathltheir `upper port; a vertical vshaft'.extending from" said accessible passagethe region ofthe juncture of the' heating flue with the regenerator therefor, individually connecting the lower part of a heating flue of said vwall with the upper part of said regenerator; anadjustable flow vrestricting element for the regenerator duct-'means positionedbetween the lowerpart o'f saidheating flue and the upper part of said re'- generator and adapted to modify the cross-sectional area 4of saidregenerator ductrneans in; such manner that gases flowed therethrough are susceptible of regulation independently of regenerator duct means for other heating flues of said heating wall; and adjustable regulating means extending downwardly from the flow restricting means into the accessible passageway and operative from beneath the oven-supporting mat for actuating said flow restricting element to adjust the same from within the accessible passageway beneath the oven mat of the oven. c Y

2. A coke oven having accessible passageways beneath a supporting-mat therefor; l,a coking chamber having a fiued heating wall there-adja-l cent and a regenerator therebeneath; regenerator duct means, in the region ofthe juncture ofthe heating flue with the regenerator therefor, individually connecting the lower part of a heating ue of said wall with the upper part of said regenerator; an adjustable flow restricting elementffor the regenerator duct means positioned between the lower part of said heating flue and the upper part of said regenerator and adapted to modify the cross-sectional area of saidregenverator duct-means in such manner that gases flowed therethrough are susceptible o'f'regulation independently of regenerator duct-'means for other heating flues of'said heating Wall; and adjustable regulating means extending downwardly from the flow restricting means into the accessible passageway and operative from beneath the over-supporting mat for actuating `said flow restricting element to adjust the same from within the accessible passageway beneath the` oven mat of the oven; and in which the adjustable,v

flow restricting element is a member that forms essentially a part `of the duct walls of the regenerator duct means that communicably connect a heating flue with a regenerative space and in which the regulating means for said flow restricting element comprises a rod-like member that is adapted to be raised and lowered in said vertical shaft from beneath the oven-supporting mat.

3. In a regenerative coking retort oven having a horizontally elongated coking chamber and on either side thereof vertically flued heating walls that are supported by pillar Walls disposed to rest on a supporting-mat having accessible passageways therebeneath, the heating ues of the heating wallsv being each communicably connected at their lower parts individually with the `upper parts of regenerators that are positionedon opposite sides of said pillar walls by converging regenerator ducts in the region of the juncture of the heating walls with the regenerators, the duct means to any one heating flue comprising separate duct portions leading from the separate regenerator chambers and converging into, and entering the lower part of the heating ue through, an .upper common port, in combination:

for individual heating ues, a movable brickways upwards through `a pillar wall and intersecting 'said ductjmeans; means for retainingsaid lmovable brick-valve-element adjustable with re.-

spect -to .said vertical shaft; and means, operative valve-elementlin'a manner to modify the effectiveicross-sectional area tof` the duct means that; connect' the heating `flue and regenerators. 214.- [A regenerative coking retort oven as claimed in'iclaim'3-11an-d in which-the movable brickis formedfto constitute `a-*segment of the-walls of Lthe duct means and isretained in position by a stem-like-projection that is adapted to slideably fit into the vertical shaft ofthe pillar Wall'.

5. A regenerative coking retort'oven asclaimed c in claim `3 and in which the movable brick is formed vto vconstitute a segment of the walls of the duct means 'and is provided with lateral nlike members that in effect operate to separate the converging portion of the duct means that lead from the respective regenerators when the movable brick is elevated in a vertical plane.

: 6. A regenerative coke oven as claimed in claim 3, and in which the movable brick-valve-element comprises a plug member adapted to modify the area of the kupper, .common port which connects the converging duct portions of the Aconverging duct means, said plug member being removably supported by and actuated with a lowerdamper member*adapted'to` further modify the effective area of the duct means over the modification by the plug member when actuated for the purpose.`

7. A regenerative coke oven having accessible passageways beneath a supporting-mat therefor;

a coking chamber havinga flued heating wall there-adjacent and a regenerator therebeneath; regenerator duct means, in the region of the juncture of the heating ue with the regenerator therefor, individually connecting the lower part of a heating flue of said w'alljwith the upper part of said regenerator; an adjustable flow restricting element for the regenerator duct-means positioned between the lower part of said heating nue and the upper part of said regenerator and adapted to modify the cross-sectional area of saidv regenerator duct-means in such manner that gases flowed-therethrough are susceptible of regulation independently of regenerator ductmeans for other heating flues of said heating wall; and adjustable regulating vmeans extending downwardlyfrom the flow restricting means into theacessible passageway and operative from beneath theoven-supporting mat Ifor` actuating said flowrestricting element to adjust the same from within the accessible passageway beneath the oven mat of the loven; and in which the adjustable flow restricting element comprises a lower member which itself forms a part of the` walls of the duct means and is adjustable relative to the rest ofthe walls of the duct means to increase and decrease the`v cross-sectional area of the duct means, and an upper member movablewith the movement of the lower member, removably mounted on the same for exchange with other like members of different sizes, and adapted `to maintain a constant cross-sectional area in the portion of the duct means it dampens in any adjusted position of Ithelower member.

sol

8.- A regenerative coke oven having accessible c passageways beneath a `supporting-mat therefor; a coking chamber having a flued heating wall there-adjacent and a regenerator therebeneath;

regenerator duct means, in. the region; of the juncture of the heating flue with the regenerator therefor, individually connecting thei lower part cfa heating flue of' said wall. with the upperL part ofY said regenerator;l an adjustablefow restrict` ing element for the regenerator duct-meanspositioned between the, lower part of said heating t flue and the upper part of saidregenerator and adapted to modify the crossl-sectional area of said regenerator duct-means; in such manner that. gases owed therethrough are susceptible of regulation independently of regenerator ductmeans for other heating ues of said heating Wall; and adjustable regulating means extending 

